Digital timestamps record date and time information and may be attached to digital data. For example, computer files contain timestamps that tell when the file was last modified, and digital cameras add timestamps to the pictures they take, recording the date and time the picture was taken. Computers use digital timestamps to control access to licensed media content, such as a movie. When an application begins playing the movie, the application may request a timestamp from a hardware real time clock to monitor when the license expires so that the licensed media content is not available beyond expiration of the license. An attacker can cause the real time clock to be reset before the license associated with the media content expires and thereby bypass the license to obtain unlimited access to the media content.